1. Field of the Invention:
This invention relates generally to structures having controlled thermal expansivity, that is a controlled dimensional change in response to temperature change. More particularly, the invention relates to such a structure whose linear thermal expansivity along a given axis is adjustable through a range which may include zero expansivity and whose thermal expansivity and overall length along the axis are adjustable independently of one another.
2. Prior Art:
Many mechanical structures for use in a thermal environment whose temperature varies over a substantial range are required to have a controlled thermal expansivity. Most structures of this kind, for example, are designed to have essentially zero thermal expansivity so as to undergo little, if any, dimensional change in response to changing temperature. A structure having such zero or near zero expansivity is commonly referred to as a dimensionally stable structure. Examples of such dimensionally stable structures are found in U.S. Pat. Nos.:
1,987,372 PA1 3,077,958 PA1 3,201,076 PA1 3,229,224 PA1 3,412,551 PA1 3,468,080 PA1 3,528,206 PA1 3,675,376